No American President has ever spoken to the world like this.
In his United Nations General Assembly debut, Trump applied the disruptive, bellicose, nationalistic persona that shattered US political norms and signaled an attempt to transform America's role in the world and the international system itself.
"We must work together and confront together those who threaten us with chaos, turmoil and terror," Trump said in a survey of global geopolitics that paralleled his stark inaugural address eight months ago.
It was dark, desolate, had a whiff of authoritarianism and pulsated with threats: None of his predecessors, for instance, stood in the well of the UN chamber and threatened to wipe a country -- in this case, North Korea -- off the face of the planet. It was the "axis of evil" on steroids as the President blasted "rogue states" and trumped George W. Bush-era rhetoric to put Pyongyang, Iran, Venezuela and Cuba on notice.
"It certainly was, in many ways quite a groundbreaking speech," said Nile Gardiner, an analyst at the conservative Heritage Foundation, who praised Trump for his "assertive and aggressive" delivery and for breaking with the more "deferential" multilateral doctrine of the Obama administration.
Substance and bombastBut though Trump's threats took the headlines, his address -- the most encompassing summation of his global vision that he has ever attempted -- contained substance as well as bombast.
It provided a blueprint for global Trumpism and tried to mold the anti-globalist anger that powered the President's campaign and populist movements around the world, into a coherent, international theory.
It was also a sign that though many advocates of economic nationalism have left his administration, the philosophy burns deep in his heart.
Trump's supporters, to whom this speech was partially aimed as he fogs some campaign positions on immigration, will delight in the "tough guy" imagery and a vision that was free of nuance and political correctness.
But foreign leaders already wary of Trump's approach, whom he may call upon for military sacrifice at some point, may question his call for burden sharing when he did not even mention the threat that many see as paramount, the one posed by global warming.
And as always with Trump there are questions of constancy and tone. He's never been bound by doctrine or principle and would surprise no one if he tweeted sentiments that contradict his big UN appearance in the days ahead. He has already turned some heads, toasting the "potential" of the UN on Tuesday, after railing against the organization for years.
Yet taken at face value, Tuesday's speech may be seen by history as a signature moment in the Trump presidency.
The former real estate magnate and reality star effectively drew a line under 70 years of US leadership that has generally, though not exclusively, sought to rally the world behind a common vision of internationalism.
Instead, he offered "principled realism" -- a concept that allows "sovereign" nation states the right to pursue their own self interests unencumbered by bureaucracy, global trade deals or multilateralism -- a vision that is not only germane to Trump's political principles, but reflects how he has lived his life.
It turns out that "America First" doesn't just mean the US can chase its individual self interests -- but everyone else can, too -- a concept likely to find favor in capitals like Moscow and Beijing where the concept of "sovereignty" that was a repeatedly endorsed by Trump, is a bedrock political value.
TheatricsAnd while the UN chamber is antiseptic, and suffocated in the rituals of diplomacy, Trump brought his singular theatrics.
From a spot where dictators and demagogues have harangued delegates, including Cuba's Fidel Castro and Iran's Mahmoud Ahmadinejad, the President, dipped into his Twitter vernacular to roast North Korea's Kim Jong Un as "Rocket Man," to brand terrorists "losers" and warned that some nations were "going to Hell."
Trump's 41-minute address may mark the moment that dictated a fateful course for US policy towards North Korea and Iran.
"The United States has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea," he said.
Some may argue that the President's threat was simply a reiteration of the vow that the US would respond overwhelmingly if a nuclear weapon was ever used against the US or its allies.
But his casual threat of the use of nuclear weapons was chilling coming from an American President. And it appeared to reflect a decision by the administration that increasing threats against Kim could cause him to capitulate -- even though Trump's bellicosity has utterly failed to halt North Korea's accelerating bid to twin a nuclear bomb with a long range missile.
"It's almost as if he was advised that upping the rhetoric will intimidate, or can have some intimidation effect on Kim Jong Un. I think that is a very risky proposition. I don't see any evidence that is the case," said former State Department spokesman John Kirby, who is now a CNN analyst.
A senior UN official told CNN's Jim Scuitto that shock reverberated through the chamber when Trump made his threat.
"You could feel a wind had gone into the room when he said that. People were taken aback. There were rumblings. It is as an emotional reaction."
Trump's language on Iran was just as striking, as he signaled a return to the Cold War that has prevailed between Tehran and Washington since the Islamic Revolution in 1979 and gave the strongest sign yet that he will pull out of the nuclear deal agreed during a brief thaw in relations under Obama.
"Frankly, that deal is an embarrassment to the United States, and I don't think you've heard the last of it, believe me," Trump said.
Yet Trump offered no details, of how he will prevent Tehran resuming its race towards a nuclear bomb if the deal collapses, or how he will martial support of most US allies who strongly back the Iran deal.
Trump's critics found his saber rattling distasteful, and alarming.
"The goals of the United Nations are to foster peace and promote global cooperation. Today, the President used it as a stage to threaten war," said Democratic Sen. Dianne Feinstein. "He missed an opportunity to present any positive actions the UN could take with respect to North Korea, and he launched a diatribe against Iran, again offering no pathway forward."
Global TrumpismAnd while Trump laid the foundations of the theory of global Trumpism -- his philosophizing was laden with contradictions.
He lauded the Marshall Plan that rebuilt Europe after World War II, one of the great achievements of American foreign policy. But his apparent relegation of values like human rights and democracy promotion appears to ignore the moral leadership role that Washington has played in the Western alliance in the 70 years since.
Similarly, Trump's rejection of global trade deals and multilateral approaches to common problems may threaten the soft power influence that has underwritten American global dominance for decades.
The abandonment of the Trans-Pacific Partnership trade deal for instance has offered a clear opening for China to quicken its rise in region, and to challenge a US-led system of global economic rule making.
And Trump's willingness for other nations to pursue their self interests in preference to common goals also appears selective.
He slammed socialism in Venezuela, for example, and clearly challenged the sovereignty of North Korea and Iran.
"There were a lot of contradictions ... we're going to respect the sovereignty of other people ... but what was ironic, in many cases he talked about countries that the United States was not prepared to live with, like North Korea, but because of the way they treat their inhabitants," said Patrick Stewart, a senior fellow at the Council on Foreign Relations.